<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    let a=parseInt(prompt("请输入长方形的长"));
    let b=parseInt(prompt("请输入长方形的宽"));
    function f(a,b) {
        return a*b;
    }
    let s=f(a,b);
    alert(s)
</script>
</body>
</html>